Re: [PATCH v3 1/2] tty: hvc: pass DMA capable memory to put_chars()

[Xianting Tian]

在 2021/8/5 下午4:09, Jiri Slaby 写道:
> On 05. 08. 21, 9:58, Jiri Slaby wrote:
> > Hi,
> >
> > On 04. 08. 21, 4:54, Xianting Tian wrote:
> > > @@ -933,6 +949,16 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, 
> > > int data,
> > >       hp->outbuf_size = outbuf_size;
> > >       hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
>
> This deserves cleanup too. Why is "outbuf" not "char outbuf[0] 
> __ALIGNED__" at the end of the structure? The allocation would be 
> easier (using struct_size()) and this line would be gone completely.
I will make the cleanup in v4.
> > > +    /*
> > > +     * hvc_con_outbuf is guaranteed to be aligned at least to the
> > > +     * size(N_OUTBUF) by kmalloc().
> > > +     */
> > > +    hp->hvc_con_outbuf = kzalloc(N_OUTBUF, GFP_KERNEL);
> > > +    if (!hp->hvc_con_outbuf)
> > > +        return ERR_PTR(-ENOMEM);
> >
> > This leaks hp, right?
>
> Actually, why don't you make
> char c[N_OUTBUF] __ALIGNED__;
>
> part of struct hvc_struct directly?
thanks, it a good idea, I will change it in v4.
> > BTW your 2 patches are still not threaded, that is hard to follow.
> >
> > > +
> > > +    spin_lock_init(&hp->hvc_con_lock);
> > > +
> > >       tty_port_init(&hp->port);
> > >       hp->port.ops = &hvc_port_ops;
> >
> > thanks,